The invention relates to a color display device comprising a color cathode ray tube including an in-line electron gun for generating three electron beams, a color selection electrode and a phosphor screen on an inner surface of a display window and a means for deflecting the electron beams across the color selection electrode.
Such color display devices are known.
The trend is towards display windows having a flatter outer surface, so that the image displayed by the color display device is perceived as being flat. However, as the radius of curvature of the outer surface increases, a number of problems increase accordingly. The radius of curvature of the inner surface of the display window and of the color selection electrode should increase too, and as the color selection electrode becomes flatter, the strength of said color selection electrode decreases and hence the sensitivity to doming and vibrations increases. Particularly the sensitivity of the color selection electrode to the so-called drop-test increases. An alternative would be to give the inner surface of the display window a greater curvature than the outer surface. This would enable the use of a color selection electrode with a relatively small radius of curvature. This reduces the doming and vibration problems, but it leads to other problems. The thickness of the display window in the center is much smaller than at the edges. As a result, the weight of the display window increases and the intensity of the image decreases substantially towards the edges.